A single dose of clonazepam may be used to reduce the intensity of congenital nystagmus or to eliminate it altogether for a short period of time, allowing assessment of underlying visual acuity without visual impairment due to retinal image slip. An oculographic study in spasmus nutans shows that head turning transiently dampens the nystagmus. The nystagmus present in rod monochromaticity showed a predominantly pendular wave form.